The liberal activist says Trump has brought some important issues to the fore.

"He's questioned the trade agreements. He's done some challenging of Wall Street-- I don't know how authentic that is. He said he's against the carried interest racket, for hedge funds. He's funded himself and therefore attacked special interest money, which is very important," Nader says. "But he's lowered the level of political debate to unheard-of depths of salacious, slanderous and vacuousness, garnished with massive self-boosterism and repetition."

"And that's not good, because that brought a lot of money into the media and that's the kind of debates they're going to want to goad."

When asked what positive contributions Clinton has made to the 2016 campaign, Nader called her a "corporatist, militarist Democrat" who would have been defeated by Sanders if every state held an open primary.

"She's going to win by dictatorship. Twenty-five percent of superdelegates are cronies, mostly. They weren't elected. They were there in order to stop somebody like Bernie Sanders, who would win by the vote," he says.